PIEZO1 and free sialic acid storage disease, infantile form: Zhou et al. (2021) demonstrated that WES should be offered to all hydropic fetuses, especially recurrent nonimmune fetal hydrops cases, regardless of whether hydrops are isolated or are in presence of structural abnormalities. Many monogenic disorders predisposing to nonimmune fetal hydrops (OMIM #236750) have been illustrated such as erythropoietic porphyria (UROS), Gaucher disease (GBA), infantile sialic acid storage disease (SLC17A5), mucopolysaccharidosis type VII (GUSB), glycogen storage disease IV (GBE1), and LMPHM6.